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From: Geode on 12 May 2010 17:23
I have always been puzzled how they reasoned the number of molecules
in a mol.
But I have never find a clear process to state this number.
Does anyone had read about it?
Geode
..
From: Sam Wormley on 12 May 2010 17:36
On 5/12/10 4:23 PM, Geode wrote:
> I have always been puzzled how they reasoned the number of molecules
> in a mol.
> But I have never find a clear process to state this number.
> Does anyone had read about it?
> Geode
> .

See: http://en.wikipedia.org/wiki/Avogadro_constant

"The value of the Avogadro constant was first indicated by Johann Josef
Loschmidt who, in 1865, estimated the average diameter of the molecules
in air by a method that is equivalent to calculating the number of
particles in a given volume of gas.[7] This latter value, the number
density of particles in an ideal gas, is now called the Loschmidt
constant in his honour, and is approximately proportional to the
Avogadro constant. The connection with Loschmidt is the root of the
symbol L sometimes used for the Avogadro constant, and German language
literature may refer to both constants by the same name, distinguished
only by the units of measurement.[8]"
From: Uncle Al on 12 May 2010 18:10
Geode wrote:
>
> I have always been puzzled how they reasoned the number of molecules
> in a mol.
> But I have never find a clear process to state this number.
> Does anyone had read about it?
> Geode
> .

Depends on the mole. Any unit of mass is good - gram, kilogram,
ounce, pound, ton - to get a consistent system. 12 grams of C-12 is
Avogadro's Number of carbon atoms. South of the border, Avocado's
Number will get you a guacamole.

And you deserved it.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz4.htm
From: Hawkman on 12 May 2010 18:25
On May 13, 12:36 am, Sam Wormley <sworml...(a)gmail.com> wrote:

> "The value of the Avogadro constant was first indicated by Johann Josef
> Loschmidt who, in 1865, estimated the average diameter of the molecules
> in air by a method that is equivalent to calculating the number of
> particles in a given volume of gas.[7]

But how can molecules have a diameter if they are not circles? Only
circular shapes have a diamter but molecules are not circular.
From: Uncle Al on 12 May 2010 19:19
Hawkman wrote:
>
> On May 13, 12:36 am, Sam Wormley <sworml...(a)gmail.com> wrote:
>
> > "The value of the Avogadro constant was first indicated by Johann Josef
> > Loschmidt who, in 1865, estimated the average diameter of the molecules
> > in air by a method that is equivalent to calculating the number of
> > particles in a given volume of gas.[7]
>
> But how can molecules have a diameter if they are not circles? Only
> circular shapes have a diamter but molecules are not circular.

If they are above absolute zero and they are molecular they are
spinning - read your P-Chem book about the specific heats of gases.
Can you find the average diameter of an ellipsoid? Can you do a BET?

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz4.htm
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